Helicopter rotor head assembly



March 23, 1954 R. P. ALEX HELICOPTER ROTOR HEAD ASSEMBLY 5 Sheets-Sheet 1 Original Filed May 20, 1947 RALPH PAUL ALEX F 1 3 INVENTOR BY 7' /flafiu ATTORNEY March 23, 1954 R. P. ALEX HELICOPTER ROTOR HEAD ASSEMBLY 5 Sheets-Sheet 2 Original Filed May 20. 1947 RALPH PAUL ALEX INVENTOR BY My? KS6 mama "65m 52.

xorrm JOKPZOO ATTORNEY March 23,1954. Q E E 2,672,940

HELICOPTER ROTOR HEAD ASSEMBLY Original Filed May 20. 1947 5 Sheets-Sheet 3 AUTOROTATIVE 'POSITION BLADE PITCH CONTROL HORN g FLAPPING 58 POWER ON,

HINGE DAMPER POSITION 98 132 BLADE ST 96 J 82 v 66 BLADE STOP TOTAL PITCH CONTROL FORWARD RALPH PAUL ALEX v INVENTOR ATTORNEY March 23, 1954 R. P. ALEX 2,672,940

HELICOPTER ROTOR HEAD ASSEMBLY Original Filed May 20, 1947 5 Sheets-Sheet 4 g DRAG HINGE /4 Q FLAPPING 7 HINGE 52 fi-tu PITCH CONTROL BLADE REST 86 TORQUE SC i SSORS PITCH CONTROL R0 D 1%" LATERAL I28 CONTROL T TA pl T INCREASE CONTROL PITCH DECREASE PITCH I FORWARD RALPH PAUL ALE X INVENTOR ATTORNEY March 23, 1954 R. P. ALEX ER ROTOR HEAD ASSEMBLY HELICOPT Original Filed May 20, 1947 5 Sheets-Sheet 5 BLADE ROTATION LATERAL CONTROL TOTAL PITCH CONTROL PORT FORWARD AFT STARBOARD lNCREASE i! 54 STIGK j [l] DECREASE AZIMUTH CONTROL G W T A HS m U P WM 20 AC I56 RALPH PAUL ALEX INVENTOR BY 47 a (7 ATTORNEY Patented Mar. 23, 1954 aftNG. .0. .1 ,n ela ware hEajrfielg, Conm, assignor to United ati n, Eastfiartt rsl Gum-ha;

:Qxifihal; applicatiom-May 202;:19422, :Serialu No.

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materially reduced."

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Another object isto proyidg ahelicppter where h s rr l s fl h lwax rbeinor ahtmthe. flapping or coning axisg,

er iect'i n: cleieihl dere t hich. underliesthe blade in? all fligggt conflitiqrgs mrurther -objectis toqgrovide a system goj freeg floating; control -f stars which: eliminja tes contact; between =thestars-angl the rotor;driye'speitgtlms; eliminating bearing surfaces' therebetween mb e tis1tq12 oYi e-ahswashhn1ete system for-controlling he;;-b1a d e ;pitch wlligli is; s ea lws l fiedz n'dim ger tgflarpslu ei.

' An h r." bjwt-r t t'g y defi fn e trong; pitch" controh-mechenism'iggluqigg tge qp qfirgls therefor.

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rivje shaft '36 drives indt ilix' oit; gw 11s 9. arn dg. within housing '38- QQitQQlIlPIZIlHQUF-ltl il ll lmductiongear housi ing'38is the "drive takemmflfljpr the tachometer sesexat r. not nowm,. The tail" o or d ive hattfll' i ye f t 'e'hie aspeedc lrom t s ake,-

oflfi'amithe' 1 R s: t' here t 1s JBdllcedinreductiom pylo 20.; This enables the long tail; rQtQ driye shaft, 42 to be of small.

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mastitis afibrdiahwiclmrangeof visibility which sli comnatiblei. withlthe. extremem nuevera lity 2m 'qi imreft he ransparent plasticectionshon the opp,poptio,11;.Qt-v th wpilot s coma partment ampgtev lared the sun T e, otcunantsy f the -pil t mpar mnt sit: i1.-,-.b.V-- ids n, seat tflh n. ins rum nt box 50 su -nhvidesh btween hesee 8 in-a o ward-p.0- iti mwithin' thettransparemh last c e ubblet Duet: qnt p shar rotor I8. The azimuth stick 52 and the total fgrwamJ-qf e. main rot o fjth central section v of v Lrotor l8 throughl rahly dysdygreenttq-reduce the ro id s an on s i n; zimuth contmlsticlsfiha tota p ha d hr t le on rol,sti tfi andtt pt pedals fifi toaco t lh pitch and consequently the torque of th e -ta,i1-1

3 pitch stick 54 control the pitch setting of the main rotor blades 58 in a manner which will be more fully explained hereinafter.

Referring now to Figs. 6 and 7, which show the details of the hub assembly and the pitch controls, the blades 58 are of all metal construction and are fabricated according to the method disclosed in the U. S. application Serial No. 632,620 of Igor I. Sikorsky, assigned to the applicants assignee, and issued August 12, 1952 as Patent No. 2,606,728, which was copending with application Serial No. 749,256.

4 The blade pitch control horn I is integral with the rotatable sleeve I0 and the blade stub the drag hinge, this point of connection will The main rotor drive shaft 26 drives the hub through splines 60. The hub is comprised of two similar plates 62, 62 ,,which are generally triangular in plan and areseparated from each other to permit mounting the essential parts therebetween. In this construction it will be noted that the hub is fabricated in a manner similar to that employed in clockcases where all the parts are mounted between the two faces. The vertical drag hinge 64 is mounted between the two hub plates 62, 62 on substantially the extended radius of the drive shaft 26. The horizontal or flapping hinge 66 intersects the drag hinge 64 at 90. The stub shaft 68 is pivotally mounted on the flapping hinge 66. A sleeve member I0 is mounted on the stub shaft 68 by means of bearings I2 which allow the sleeve I0 freedom of rotation but prevent axial movement. The blade 58 is mounted on a spar I4 which is held fixed with respect to the sleeve I0 by means of a threaded retention member I6.

As shown in Fig. 6, the blades are in the autorotative position, i. e., the longitudinal axis of each blade is substantially aligned with a radius of the drive shaft 26. In the power-on position, the blades will drag back to the position shown in dotted lines. These two positions represent substantially the magnitude of the blade movement around the drag hinge which is desirable. Movement beyond these positions must be restrained and for this purpose blade stops I8 have been mounted vertically between the hub plates 62 by means of bolts 80. The blade stops I8 have rubber cushions'82 mounted on the contacting faces to ease the shock of contact. A paddle shaped finger 84 extends inwardly from the drag hinge pin 64 and is integral therewith. The paddle 84 cooperates with the rubber cushions 82 on the blade stops I8.

Movement of the blade 58 in a vertical plane about the flapping hinge is desirable in flight but the blade must be restrained from movement below a horizontal position so that the blade tips will not strike the ground or the tail cone I6. To restrain such movement, a blade rest 86 has been provided by merely extending a finger outwardly from the drag hinge as best shown in Fig. 7. A rubber cushion 88 is bolted on the stub shaft 68 to cooperate with the blade rest.

Movement of the blade about the flapping hinge 66 results from aerodynamic and dynamic forces and need not be restrained but movement about the drag hinge 64, resulting from the natural hunting action of the blade in forward flight, must be damped to avoid excessive vibration. Accordingly, a damper 90 is provided for each of the blades 58 and is mounted vertically between the hub plates 62. The movement of the blade about the drag hinge is transmitted to the damper arm 92 by means of a link 94 and an arm 96 which is secured on a serrated vertical extension of the vertical hinge 64 by means of alocknut 98.

always lie on the extended axis of the horizontal hinge 66. Therefore as the blade moves about the flapping hinge, there will be no Delta-3 effect, i. e., no decrease in pitch as the blade moves upwardly about the flapping hinge. If it is desired to have a Delta-'3 effect, the point of connection between the control horn I00 and the control rod I02 may be moved off the center line of the flapping hinge and away from the axis of the drive shaft 26.

The lower end of the pitch control rod I02 is pivotally connected at I04 to the rotating star I08 which is driven at rotor speed by means of torque scissors I01. The star I06 is rotatably mounted on the stationary star I88 by means of bearings IIO Which allow relative rotation between the stars but maintain them parallel. The stationary star I08 may be moved axially with respect to the drive shaft 26 or tilted in any direction by movement of the total pitch stick 54 and the azimuth stick 52 in a manner to be more fully described hereinafter. A lever H2 is pivoted at II l on an upwardly projecting arm H6 which is integral with the rotor pylon H8. The pylon IIB provides bearings II9 for the shaft 28. Since the rotor pylon H8 is part of the fuselage framework, the pivot point II4 provides a rigid stationary reference point. The left hand end of the lever I I2 is pivotally connected at I28 to rod I30. The right hand end of the lever H2 is pivotally connected by means of bearings I20 to an inner ring I22 which is pivotally connected by means of pins I24 to an outer ring I26. The lateral control arm I32 is connected to the outer ring I26 and extends generally aft and to the left with respect to the fuselage. A longitudinal control arm I34 (Fig. 8), extending aft and to the right is connected to the outer ring I26 at substantially to the lateral control arm I32.

It will be noted that the pitch control rod I02 is substantially vertical in the auto-rotative position shown in the drawings. When the blades drag back, in power-one flight, the control rod I02 will become slightly inclined. As the hunting action takes place, the blade will be damped aerodynamically aswell as by the dampers 90. Thus as. the blade drags back the control rod I02 becomes further inclined and the pitch of the blade 58 is decreased to allow the blade to swing forwardly. Conversely, as the blade swings forward, the control rod I02 approaches the vertical position and increases the pitch of the blade to cause it to move back to the normal power on position.

Movement of the rod I30 will act to increase or decrease the pitch of the blades simultaneously. As the rod is moved down, the lever II2 rotates about the pivot I I4 in a counterclockwise direction to move both stars upwardly and increase the pitch of the blades. Similarly, when the rod I30 is moved up the pitch of the blades will be decreased.

Cyclic variations in the pitch are obtained by moving the lateral or longitudinal control arms singularly or conjointly, dependent upon the diother modifications and adaptations will occur to those skilled in the art; therefore, I wish not to be limited in my invention only to the form shown and described, but by the scope of the following claims.

I claim:

1. In a rotary wing aircraft, a rotor drive shaft, a hub on said shaft including upper and lower plates spaced apart on said shaft, a plurality of rotor blades pivotally mounted between said plates each having a drag hinge extended above said upper plate, said drag hinges being journalled in said plates and being movable with their respective blades as the latter move in the plane of blade rotation, a damper for each blade submerged in said hub and having a member extended through said upper plate which is subject to the restraint imposed by said damper, first arms rigidly secured adjacent one of their ends to the extended ends of said drag hinges, second arms secured adjacent one of their ends to said damper members, and means operatively connecting the free ends of said first arms with the free ends of said second arms.

2. In a rotary wing aircraft, a rotor drive shaft, a hub on said shaft including upper and lower plates spaced apart on said shaft, a plurality of rotor blades pivotally mounted between said plates, each having a drag hinge extended above said upper plate, said drag hinges being journalled in said plates and being movable with their respective blades as the latter move in the plane of blade rotation, a damper for each blade located between said plates and having a member extended through said upper plate which is subject to the restraint imposed by said damper, first arms rigidly secured adjacent one of their ends to the extended ends of said drag hinges, second arms shorter than said first arms likewise secured adjacent one of their ends to said damper members, and linkage means connecting the free ends of said first and second arms.

3. In a rotary wing aircraft, a rotor drive shaft, a hub on said shaft including upper and lower plates spaced apart on said shaft, a plurality of rotor blades pivotally mounted between said plates, each having adrag hinge extended above said upper plate, said drag hinges being journalled in said plates and being movable with their respective blades as the latter move in the plane of blade rotation, a damper for each blade located between said plates closely adjacent said shaft and having a member extended'through said upper plate which is subject to the restraint imposed by said damper, and linkage means disposed above said upper plate for operatively connecting the drag hinge of each blade with one of said damper members including short arms fixed to said damper members and long arms fixed to-said drag hinges whereby angular movement of said dra hinge is multiplied in said damper member.

4. In a rotary wing aircraft, a rotor'drive shaft, a hub on said shaft including connected upper and lower generally triangular plates spaced apart I on said shaft, a plurality of rotor blades having drag hinges movable therewith as they move in the plane of blade rotation, said drag hinges being journalled between said plates adjacent the apexes thereof and extending through said upper plate, a damper for each blade located substantially midway between adjacent drag hinges in the space between said plates and having a member extended through said upper plate which is subject to the restraint imposed by said damper, linkage means operatively connecting'each of said drag hinges with the damper member of an associated damper including rigid arms carried by said hinges and said'members, the free ends of which are pivotally connected, the arms fixed to said drag hinges being longer than the arms fixed to said damper members, whereby angular movement of said drag hinges results in an increased angular movement of said damper members.

5. In a rotary wing aircraft, a rotor drive shaft, a hub on said shaft including connected upper and lower generally triangular plates spaced apart on said shaft, a plurality of rotor blades having drag hinges movable therewith as they move in the plane of blade rotation, said drag hinges being journalled between said plates adjacent the apexes thereof and extending through said upper plate, a damper for each blade located substantially midway between adjacent drag hinges in the space between said plates and having a mem her extended through said upper plate which is subject to the restraint imposed by said damper, linkage means operatively connecting each of said drag hinges with the damper member of an associated damper including rigid arms fixed to and movable with the extended ends of said hinges and said members, said arms being connected to said hinges and said members so as to lie close to the top surface of said upper plate and the arms of each blade and its associated damper being generally parallel with each other, and a link operatively connecting the free ends of the arm of each blade and the arm of its associated damper.

I RALPH P. ALEX.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,948,457 Larsen Feb. 20, 1934 1,986,709 Breguet et a1. Jan. 1, 1935 

